There are well-known MEK1, MEK2 and MEK1/2 inhibitors, which structure includes 1H,6H-pyrido[4,3-d]pyrimidine-2,4,7-trione [WO 2005/121142, WO 2012/088033, USA 7378423], the most advanced drug being Mekinist (Trametinib dimethyl sulfoxide, GSK1120212) [H. Abe, S. Kikuchi, K. Hayakawa et al. ACS Med. Chem. Lett. 2011, 2, 320-324]. GSK1120212 is efficient MEK1/2 inhibitor, which shows higher efficiency against u-MEK1/2 prior to C-Raf activation (u-MEK1: IC50=0.7 nM) as compared to pre-activated one (pp-ME1: IC50=14.9 nM) [http://clincancerres.aacrjournals.org/content/17/5/989.full].

However, Trametinib and Mekinist are practically insoluble in aqueous media between pH=2 and pH=8. Trametinib and Mekinist are also very slightly soluble in organic solvents including highly polar ones (sparingly soluble in hot aprotic solvents).
This is why compounds, which may demonstrate favorable efficiency profiles with regard to ME1, ME2 and ME1/2, and high solubility in aqueous or organic solvents, are still in demand. Due to improved bioavailability these compounds are expected to be more suitable as cancer therapeutic agents.
Besides that, although Mekinist has low single-dose oral toxicity (LD50>2000 mg/kg for mice), critical weight loss or sometimes even animal deaths are observed during long-term high dose level administration. Thus, a search of lower long-term dosage toxicity products of this group remains very important.
The aim of the present invention is to create novel MEK1, MEK2 and MEK1/2 inhibitors which have lower toxicity in long-term dosage.
This aim is achieved by the novel compound N-{3-[3-cyclopropyl-5-(2-fluoro-4-iodophenylamino)-6,8-dimethyl-2,4,7-trioxo-3,4,6,7-tetrahydro-2H-pyrido[4,3-d]pyrimidin-1-yl]-phenyl}-cyclopropanecarboxamide dimethyl sulfoxide solvate of formula 1.